Close Space Sublimation as a Versatile Deposition Process for Efficient Perovskite Silicon Tandem Solar Cells

The envisaged breakthrough of perovskite photovoltaic technologies demands rapid advances in scalable and robust high-throughput fabrication methods. Here, we present close-space sublimation (CSS) as a vacuum-based, industrially relevant deposition method for the conversion of sublimed PbI2 inorganic scaffolds into high-quality wide-bandgap perovskite absorbers (MAPb(I0.79Br0.21)3, 1.64 eV), employing a reusable mixed-halide organic source for stable bandgap control. We provide mechanistic insights into the substitution-reaction-limited CSS process and achieve PCEs of up to 18.5% for fully vacuum-processed p-i-n single-junction devices. Monolithic integration onto planar, nano-, and micro-textured silicon bottom cells reveals consistent optoelectronic and morphological properties across all configurations without requiring adjustments of deposition parameters, as corroborated by comprehensive characterization techniques. The resulting perovskite/silicon tandem solar cells reach PCEs up to 24.3%, with minimal variation across the different bottom cells. Our findings highlight the broad process window and versatility of CSS, positioning it as an industry-suitable deposition method for solvent-free high-throughput fabrication.